Hitherto, as means for correcting a white defect or a black defect that occurs in a photomask or a FPD (Flat Panel Display), a laser CVD (Chemical Vapor Deposition) method has been used to correct the white defect, and a laser repair method that removes an unnecessary residual defect with a laser beam has been used to correct the black defect.
Since, in many cases, wavelengths of the laser beams used for each of the aforementioned correction means are different from each other, in a case that the aforementioned two types of defects are corrected, laser oscillators that irradiate laser beams having different wavelengths respectively, and separate laser processing apparatuses including the laser oscillators have been used.
However, when both of the white defect and the black defect exist in the same sample, or when both defects need to be corrected, or the like, it is necessary to first mount the sample on one of the laser processing apparatuses for correcting the white defect, for example, then to mount the sample on the another laser processing apparatus for use correcting the black defect. A heavy workload, such as mounting the sample, adjusting a position, or the like, is involved and has been one cause in obstructing improvement of work efficiency. Further, as it is necessary to prepare the laser processing apparatuses for each type of repair, respective costs required for correcting the defects may not be disregarded.
Accordingly, it is desirable to have one laser processing apparatus provided with two laser oscillators irradiating laser beams of different wavelengths. For example, a laser film formation apparatus provided with first and second laser beam irradiation means, and capable of performing removal of film interconnection and a new film formation is well known (for example, refer to Japanese Unexamined Patent Application Publication No. H7-66204)
However, in the laser film formation apparatus described in the Japanese Unexamined Patent Application, as first and second laser beams irradiated by the first and second laser beam irradiation means take different optical paths until reaching an objective lens disposed immediately before the sample, in designing the laser processing apparatus, there is a possibility of having an unfavorable limitation such as an increase of a size of the casing, or the like. Further, slits have to be prepared for each of the optical paths and, therefore, in a case of performing a plurality of repairs requiring only a common slit, there has been a problem that the cost for the unnecessary slit may not be reduced.
In addition, since the laser beams having different wavelengths irradiated by the first and second laser beam irradiation means respectively pass through different positions of the same objective lens, it is common for the objective lens to be formed by using a thin film having high transmission property conforming to respective wavelengths at positions where each laser beams passes. Therefore, there is concern regarding manufacturing costs of the objective lens.
There is, therefore, a need to have different types of laser processing be performable by using a laser processing apparatus without requiring a special optical system in an optical path of laser beams, to reduce the size of the laser processing apparatus, and to provide the apparatus at low cost.